(1) Field of the Invention
This invention relates to CMOS pixels using a vertical structure and sub-micron processes. More particularly the invention relates to pixels which can detect red, green, and blue signals without the need for color filters and to pixels which use a deep N well and a P well as a gate in a vertical charge transfer active pixel sensor.
(2) Description of the Related Art
In the use of pixels for digital imagers, color filters are often used to separate color information into appropriate color signals. It is advantageous to use pixels which can provide color separation without the need for color filters.
U.S. Pat. No. 5,965,875 to Merrill describes a digital imager apparatus which uses the differences in absorption length in silicon of light of different wavelengths for color separation. A preferred imaging array is based on a three-color pixel sensor using a triple-well structure.
U.S. Pat. No. 6,111,300 to Cao et al. describes a color detection active pixel sensor. The device includes a number of doped regions. The doped regions conduct charge when receiving photons of different wavelengths.
U.S. Pat. No. 6,465,786 B1 to Rhodes describes a photodiode photosensor for use in a CMOS imager exhibiting improved infrared response.
U.S. Pat. No. 6,455,833 B1 to Berezin describes a CMOS image sensor using two or three superposed layers. Each pixel in the image sensor includes a plurality of superposed photosensitive PN junctions with individual charge integration regions.